Beneficial Insect Spotlight: Lady Beetle
I have been seeing more lady beetles in the garden lately, both on the wildflower patch and on the sunflowers. Since I was able to snap a few good pictures, I thought that I should add the lady beetle to our Beneficial Insect Files. They are, after all, one of the most beneficial bugs for gardeners and the one we hear the most about. In fact, lady beetle harvesting has become a booming business in recent years, with hundreds of thousands of beetles being purchased and shipped throughout the U.S. every year for commercial and private growers.
Lady beetles are more commonly known as ladybugs in the United States and Ladybirds in other parts of the world. They are not true bugs, but beetles, so the most common names are actually misnomers (Beetles worldwide get offended at being called bugs, and it is quite obvious that lady beetles are not birds!). Other nicknames include: lady fly, ladyclock and lady cow.
Whatever they may be called popularly, they are formally known as coccinellids (pronounced cox-ih-NEL-ids), a member of the beetle family. Coccinellids are found natively on almost every continent and there are an estimated 5,000 species with nearly 500 individual species in North America alone.
The life cycle of the lady beetle spans from three to six weeks dependent upon certain environmental factors such as humidity and temperature. With the arrival of spring, hibernating adult female beetles emerge and,after a good feast, begin laying up to three hundred light-yellow eggs on the underside of leaves in small clusters of up to fifty eggs. In under a week, small larvae emerge and they begin feeding their voracious appetite. Larvae can consume several hundred adult aphids during this stage, which generally lasts two to three weeks. All of this eating finally triggers a pupa stage that lasts a week to ten days, after which time the adult beetle emerges. Lady beetles emerge yellow to orange with no spots. It takes several hours for the spots to form and up to a few days for the outer wings (called elytra) to turn their familiar red color.
In some areas, there may be up to six generations per year(1).
Lady beetles are equipped with several defense mechanisms, the first of which is their bright red coloration, a universal warning to predators. When threatened, lady beetles also secrete a foul-smelling and bad-tasting chemical, which is called “reflex bleeding”. If this fails to divert the predator, lady beetles can also play dead like an opossum! Finally, they do have mandibles. While there are reports of humans being bitten by a lady bug, there is no venom, poison or allergic saliva to cause any harm. It may pinch a little, but more harm is caused by the shock of being bitten by such a cute insect!
Lady Beetle Collection for Commercial Sale
The majority of lady beetles collected for sale are obtained in the California mountains where they naturally gather in the millions in colonies. While lady beetles are beneficial insects to have in the garden, certain studies have shown that non-native beetles that are introduced into the garden are far less effective than native species in controlling and eliminating pests. According to these studies, “shipped-in beetles” tend to fly away, have no appetite for food, or eat far fewer pests than native species also studied – depending upon what time of year they are collected. Those collected in winter or early spring for spring release, for example, were found to be far less likely to stay put in one area. If you are a gardener buying in lady beetles to control aphids in your garden, however, you want them to stay in your garden not fly away! As such, the conclusion of the study was that “It would be better to rely upon local beetles to distribute themselves and multiply in accordance with nature’s balance” (2).
Attracting Lady Beetles To Your Garden
Given that certain studies show the ineffectiveness of releasing non-native lady beetles into the garden for pest control, it makes sense to do what one can to attract native species instead.
Lady beetles must have a food source. Their favorite is aphids, but some species are also known to eat a variety of pests including hornworms, cabbage worms and scale insects. Lady beetles also eat pollen for protein and are drawn to certain types of plants. If you want to attract lady beetles, the most effective plants are those of the mustard family, as well as certain grains and legume, cilantro, clover, fennel, dill, coreopsis, cosmos, marigolds, dandelions and yarrow. Try planting a variety of these to bring these beneficial insects to your garden (3).
Fact: An adult lady beetle must consume around 300 aphids before it starts laying eggs. A lady beetle must eat from three to ten aphids for each egg it will lay. In its lifetime, a lady beetle will consume up to 5,000 aphids.
Myth: A common myth is that the number of spots on its back indicates its age